Solid colors can be rather boring. There's noting like a nice gradient effect to jazz up a design. A gradient is a blending of one color into another...usually a darker color into a lighter color. The most common is a solid to white gradient effect. The end result is a very attractive embellishment to the overall design style. While this effect can make your logo very attractive, it is important to consider some limitations.
A logo with a prominent gradient can look a bit strange when faxed. The effect is largely lost and the end result is a blurry look at the other end. For a design that has to look good for faxing and generic black/white photocopying, this effect is not recommended. Also, this effect does not translate very well to T-Shirts and Mugs. It does translate well to professional printed business cards and stationery, and works perfectly well for the Internet in JPEG format.
The graphic below shows the progression from a solid Pantone color to a gradient color effect. The circle at left is a solid Pantone 307. The middle circle has the solid circle with a smaller inner circle set at Pantone 307 with a 0% color setting. These two circles are blended to created the gradient circle at right.
Multiple color blending effects can be used in CMYK mode, rather than just two with spot colors. The graphic below shows three possible gradient effects. The first square at left shows a two-color effect. The second design shows a three-color effect, and the third example on the right shows a multi-colored gradient effect.
Again, when your logo will be used heavily in faxing and black and white copying, this effect should not be used. If not then using gradients can be an attractive addition to your design.